A £2m estate five years ago would be worth £2.8m today due to house price and stock market growth, according to advisers Lycetts Financial Services. 

The death tax bill for a married couple would now cost £460,000, up from £400,000 before. 

A life-policy payout, written into trust, meaning it is IHT-free, can be used to cover the future bill in place of assets from the estate.

The cost of cover via a 20-year life policy at 55 would have cost £55 a month five years ago. 

But the couple would be left with a £60,000 shortfall and be unable to cover the larger bill today, unless they increased their premiums to £112 a month, the firm said.

Advisers are now urging people to review their plans to make sure they can still afford future bills. 

It follows a freeze in the £325,000 IHT allowance and £175,000 home allowance announced at the March Budget, which is expected to almost double the number of people forced to pay the tax – meant for the rich, but increasingly a burden of the middle class. 

The £325,000 IHT protection has not risen since 2009 and will not increase until 2026 at the earliest.